Kerala SSLC Biology Chapter 6 Notes Unravelling Genetic Mysteries English Medium
The similarities between parents children are due to the transmission of characters from parents to offsprings. But are the characters of parents alone transmitted to offsprings? Why is it that only some of the characters of parents are expressed in offsprings? How do differences also occur along with similarities? Such questions and the assumptions related to them have arisen since very ancient times. This unit unravels the genetic mysteries.
→ Heredity : The transmission of features of parents to offsprings.
→ Variations : The features seen in offsprings that are different from their parents.
→ Genetics : The branch of science that deals with heredity and variation is called genetics.
→ Gregor Johann Mendel is considered as the father of Genetics.
→ Allele : A gene that controls a trait has different forms. The different forms of a gene are called alleles.
→ Two scientists, James Watson and Francis Crick, presented the double helical model of DNA.
→ Nucleotides: The units by which DNA molecule is made up of.
→ A nucleotide contains a sugar molecule, a phosphate molecule and a nitrogen base.
→ Protein molecule is synthesized by adding Amino acids as a result of action of mRNA, tRNA, rRNA.
→ The genetic constitution of female is 44
→ Crossing over: During the initial phase of meiosis, chromosomes pair and exchange their parts.
→ When gametes undergo fusion, the combination of allele changes.
→ Mutation : A sudden heritable change in the genetic constitution of an organism.
→ The XY Chromosomes of the father determine whether the child is male or female.
→ The change in skin colour, dark or light, is an adaptation to live under the sun.